TDM MIMO FMCW Radar

This is a time-division-multiplexing (TDM) multiple-input and multiple-output (MIMO) FMCW radar simulation example based on RadarSimPy.

RadarSimPy is a radar simulation package built with python. Contact me if you are interested in this module.

This notebook is available on my GitHub.

Radar Model

Transmitters

For TDM configuration, time_offset parameter controls the time offset between transmitter channels. time_offset can be a single number, which means the next transmiter channel is delayed by the same time. time_offset can also be an array. The length of the array must be the same as the channel number.

The following tables list the basic parameters of the 4-channel radar transmitter. (The number of channels is determined by the size of transmitter array)

Tx Channel 1

Parameter Variable in RadarSimPy Value
Center frequency ($f_c$) fc 24.125 GHz
Bandwidth ($B$) bandwidth 100 MHz
Transmitted power ($P_t$) tx_power 10 dBm
Rising or falling chirp slop_type rising
Chirp repetition period ($CRP$) repetition_period 400 us
Chirp length ($T$) pulse_length 80 us
Number of chirps pulse_counts 256
Chirp start delay delay 0 s
Channel transmit time offset time_offset 0 s

Tx Channel 2

Parameter Variable in RadarSimPy Value
Center frequency ($f_c$) fc 24.125 GHz
Bandwidth ($B$) bandwidth 100 MHz
Transmitted power ($P_t$) tx_power 10 dBm
Rising or falling chirp slop_type rising
Chirp repetition period ($CRP$) repetition_period 400 us
Chirp length ($T$) pulse_length 80 us
Number of chirps pulse_counts 256
Chirp start delay delay 0 s
Channel transmit time offset time_offset 100 us

Tx Channel 3

Parameter Variable in RadarSimPy Value
Center frequency ($f_c$) fc 24.125 GHz
Bandwidth ($B$) bandwidth 100 MHz
Transmitted power ($P_t$) tx_power 10 dBm
Rising or falling chirp slop_type rising
Chirp repetition period ($CRP$) repetition_period 400 us
Chirp length ($T$) pulse_length 80 us
Number of chirps pulse_counts 256
Chirp start delay delay 0 s
Channel transmit time offset time_offset 200 us

Tx Channel 4

Parameter Variable in RadarSimPy Value
Center frequency ($f_c$) fc 24.125 GHz
Bandwidth ($B$) bandwidth 100 MHz
Transmitted power ($P_t$) tx_power 10 dBm
Rising or falling chirp slop_type rising
Chirp repetition period ($CRP$) repetition_period 400 us
Chirp length ($T$) pulse_length 80 us
Number of chirps pulse_counts 256
Chirp start delay delay 0 s
Channel transmit time offset time_offset 300 us

The transmitter array consists of 4 antenna elements with a $2\lambda$ spacing. Both of the transmitter antenna elements have the same radiation pattern $\cos{\theta}$. The gain of the transmitter antenna elements is 6 dB.

Receiver

The parameters of the receiver are listed in the table below.

Parameter Variable in RaSim Value
Sampling rate ($f_s$) fs 2 Msps
Noise figure ($NF$) noise_figure 12 dB
RF gain/loss ($G_{rf}$) rf_gain 20 dB
Load resistor ($R_L$) load_resistor 500 $\Omega$
Baseband voltage gain ($G_{BB}$) baseband_gain 30 dB

The receiver array consists of 8 antenna elements with a $\lambda /2$ spacing. All of the receiver antenna elements have the same radiation pattern $\cos{\theta}$. The gain of the receiver antenna elements is 6 dB.

Create the FMCW radar model based on all the parameters defined above.

Calculate the characteristics of the FMCW radar:

Targets

The propertities of targets are defined here. There are 3 targets in this simulation. The locations of the targets are defined through $(x, y, z)$ coordinates in meters, and the speeds of the targets are defined trough $(v_x, v_y, v_z)$ in $m/s$. The propertites of the targets also includes radar cross-section (RCS (dBsm)) and phase (radian).

Plot

Simulate Baseband Signals

Calculate baseband signal matrix: $$[channel, slow~time, fast~time]$$

Plot

Radar Signal Processing

Range profile

Plot

Digital Beamforming

Plot